docs(serverless): terser config example

Author: Fry98

content/faq/serverless.md

@@ -263,13 +263,22 @@ $ npx serverless offline
 Once the application is running, open your browser and navigate to `http://localhost:3000/dev/[ANY_ROUTE]` (where `[ANY_ROUTE]` is any endpoint registered in your application).
 
 In the sections above, we've shown that using `webpack` and bundling your app can have significant impact on the overall bootstrap time.
-However, to make it work with our example, there's one additional configuration you must add in your `webpack.config.js` file. Generally,
-to make sure our `handler` function will be picked up, we must change the `output.libraryTarget` property to `commonjs2`.
+However, to make it work with our example, there are few additional configurations you must add in your `webpack.config.js` file. Generally,
+to make sure our `handler` function will be picked up, we must change the `output.libraryTarget` property to `commonjs2`. It's also recommended to install the `terser-webpack-plugin` package and override its configuration to keep classnames intact when minifying your production build. Not doing so can result in incorrect behavior when using `class-validator` within your application.
 
 ```javascript
+const TerserPlugin = require("terser-webpack-plugin");
+
 return {
   ...options,
   externals: [],
+  optimization: {
+    minimizer: [new TerserPlugin({
+      terserOptions: {
+        keep_classnames: true
+      }
+    })]
+  },
   output: {
     ...options.output,
     libraryTarget: 'commonjs2',